28125 Parallax Inc, 28125 Datasheet - Page 285

• Manufacturer Part Number: 28125
• Description: TEXT ROBOTICS
• Manufacturer: Parallax Inc

Specifications of 28125

• Title: Robotics with the Boe-Bot
• Product: Microcontroller Accessories
• Lead Free Status / RoHS Status: Not applicable / Not applicable

Figure 8-2: Frequencies and Zones for the Boe-Bot
In order to test the IR detector at each frequency, you will need to use
five different frequencies and test at each frequency to find out whether the IR detector
could see the object. The steps between each frequency are not quite even enough to use
the
cumbersome. You could use five different
waste of code space. Instead, the best approach for storing a short list of values that you
want to use in sequence is a command called
command is:
If the
in
could be up to 256 values in the list, but for the next example program, we will only need
5. Here is how it will be used:
P15
P14
P13
P12
P11
P10
P9
P8
P7
P6
P5
P4
P3
P2
P1
P0
X2
X3
Boar d of Education
Vdd
15 14
X4
+
Vd d
Vin
Variable
© 20 00 -2 00 3
13 12
X5
FOR
Vs s
Red
Black
Index
…
LOOKUP
FOR freqSelect = 0 TO 4
NEXT
You might be wondering why the value of zone 4 is 37.5 kHz and not 38.5 kHz. The
reason they are not the values that you would expect based on the % sensitivity graph is
because the
37.5 kHz than it does at 38.5 kHz. The frequencies listed in Figure 8-2 are frequencies you
will program the BASIC Stamp to use to determine the distance of an object.
frequencies were determined using tests similar to the ones outlined in Appendix G: Tuning
IR Distance Detection.
LOOKUP freqSelect,[37500,38250,39500,40500,41500],irFrequency
Zone 0
41500 Hz
. If
argument is 0,
loop’s
Index, [Value0, Value1, …ValueN], Variable
Index
FREQOUT
Zone 1
40500 Hz
STEP
is 1,
Value0
operator. You could use
Value1
command transmits a slightly more powerful (harmonic) signal at
Zone 2
39500 Hz
from the list inside the square braces will be placed
from the list will be placed in
Zone 3
38250 Hz
FREQOUT
Object
Object
LOOKUP
Zone 4
37500 Hz
DATA
commands, but that would be a
. The syntax for the
and
READ
, but that would be
Variable
Zone 5
No Detection
at any
Frequency
FREQOUT
. There
LOOKUP
to send
These